Nucleic acid labeling compounds

ABSTRACT

Nucleic acid labeling compounds are disclosed. The compounds are synthesized by condensing a heterocyclic derivative with a cyclic group (e.g. a ribofuranose derivative). The labeling compounds are suitable for enzymatic attachment to a nucleic acid, either terminally or internally, to provide a mechanism of nucleic acid detection.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent application Ser. No. 10/097,113, filed Mar. 12, 2002, which claims priority from U.S. provisional patent application Ser. No. 60/275,202, filed on Mar. 12, 2001. Each of these application is incorporated herein it its entirety by reference for all purposes.

STATEMENT OF RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED RESEARCH

This invention was made with Government support under contract 70NANB5H1031 awarded by the Advanced Technology Program of the National Institute of Standards and Technology. The Government has certain rights in this invention.

BACKGROUND OF THE INVENTION

Gene expression in diseased and healthy individuals is oftentimes different and characterizable. The ability to monitor gene expression in such cases provides medical professionals with a powerful diagnostic tool. This form of diagnosis is especially important in the area of oncology, where it is thought that the overexpression of an oncogene, or the underexpression of a tumor suppressor gene, results in tumorogenesis. See Mikkelson et al. J. Cell. Biochem. 1991, 46, 3-8.

One can indirectly monitor gene expression, for example, by measuring a nucleic acid (e.g., mRNA) that is the transcription product of a targeted gene. The nucleic acid is chemically or biochemically labeled with a detectable moiety and allowed to hybridize with a localized nucleic acid probe of known sequence. The detection of a labeled nucleic acid at the probe position indicates that the targeted gene has been expressed. See, e.g., International Application Publication Nos. WO 97/27317, WO 92/10588 and WO 97/10365.

The labeling of a nucleic acid is typically performed by covalently attaching a detectable group (label) to either an internal or terminal position. Scientists have reported a number of detectable nucleotide analogues that have been enzymatically incorporated into an oligo- or polynucleotide. Langer et al., for example, disclosed analogues of dUTP and UTP that contain a covalently bound biotin moiety. Proc. Natl. Acad. Sci. USA 1981, 78, 6633-6637. The analogues, shown below, possess an allylamine linker arm that is attached to the C-5 position of the pyrimidine ring. The dUTP and UTP analogues, wherein R is H or OH, were incorporated into a polynucleotide.

Petrie et al. disclosed a dATP analogue, 3-[5-[(N-biotinyl-6-aminocaproyl)-amino]pentyl]-1-(2-deoxy-β-D-erythro-pentofuranosyl)-1H-pyrazolo[3,4-d]pyrimidin-4-amine-5′-triphosphate. Bioconjugate Chem. 1991, 2, 441-446. The analogue, shown below, is modified at the 3-position with a linker arm that is attached to a biotin moiety. Petrie et al. reported that the compound wherein R is biotin is incorporated into DNA by nick translation.

Prober et al. disclosed a set of four dideoxynucleotides, each containing a succinylfluorescein dye. Science 1987, 238, 336-341. The dideoxynucleotides, one of which is shown below, were enzymatically incorporated into an oligonucleotide through a template directed extension of a primer. The compounds provided for a DNA sequencing method based on gel migration.

Herrlein et al. disclosed modified nucleoside trisphosphates of the four DNA bases. Helv. Chim. Acta 1994, 77, 586-596. The compounds, one of which is shown below, contain a 3′-amino group containing radioactive or fluorescent moieties. Herrlein et al. further described the use of the nucleoside analogues as DNA chain terminators.

Cech et al. disclosed 3′-amino-functionalized nucleoside triphosphates. Collect. Czech. Chem. Commun. 1996, 61, S297-S300. The compounds, one of which is shown below, contain a fluorescein attached to the 3′-position through an amino linker. Cech et al. proposed that the described functioialized nucleosides would be useful as terminators for DNA sequencing.

The development of novel nucleic acid labeling compounds that are effectively incorporated into a nucleic acid to provide a readily detectable composition would benefit genetic analysis technologies. It would aid, for example, in the monitoring of gene expression and the detection and screening of mutations and polymorphisms. Such a compound should be suitable for enzymatic incorporation into a nucleic acid. Furthermore, the nucleic acid to which the labeling compound is attached should maintain its ability to bind to a probe, such as a complementary nucleic acid.

Although nucleic acid labeling compounds for use as coupling agents for probes are available there is a continuing need for additional compounds that are more efficient labeling compounds. There also exists a need for compounds that have increased solubility. This will make the compounds more useful for monitoring gene expression.

SUMMARY OF THE INVENTION

The present invention relates to nucleic acid labeling compounds. More specifically, the invention provides compounds containing a detectable moiety. The invention also provides methods of making these compounds. It further provides methods of attaching the compounds to a nucleic acid. The nucleic acid labeling compounds or the present invention are effectively incorporated into a nucleic acids to provide readily detectable compositions that are useful for genetic analysis technologies. These compounds and the detectable compositions can aid, for example, in the monitoring of gene expression and the detection and screening of mutations and polymorphisms. Thus, the compounds of the invention are suitable for enzymatic incorporation into nucleic acids. Furthermore, the nucleic acids to which the labeling compound are attached maintain their ability to bind to a probe, such as, for example a complementary nucleic acid.

The present invention provides nucleic acid labeling compounds that are capable of being enzymatically incorporated into a nucleic acid. The nucleic acids to which the compounds are attached maintain their ability to bind to a complementary nucleic acid sequence.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a non-limiting set of template moieties.

FIGS. 2, 3, 3 a, 4, 5, 6, 7, 8, 9, and 10 illustrate synthetic routes to fluorescein and biotin labeled compounds of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The nucleic acid labeling compounds of the present invention have the following structure: A-T-H_(c)-L-(M)_(m)-Q, or A-T(H_(c))-L-(M)_(m)-Q, or A-T-Q wherein A is hydrogen or a functional group that permits the attachment of the nucleic acid labeling compound to a nucleic acid; T is a template moiety; H_(c) is a heterocyclic group; L is a linker moiety; M is a connecting group; and Q is a detectable moiety.

In one embodiment, the nucleic acid labeling compounds have the following structures:

wherein A is hydrogen or a functional group that permits the attachment of the nucleic acid labeling compound to a nucleic acid; X is O, S, NR₁ or CHR₂, wherein R₁ and R₂ are, independently, hydrogen, alkyl or aryl; Y is hydrogen, N₃, F, OR₉, SR₉ or NHR₉, wherein R₉ is hydrogen, alkyl or aryl; Z is hydrogen, N₃, F, OR₉, SR₉ or NHR₁₀, wherein R₁₀ is hydrogen, alkyl or aryl; L is a linker moiety; Q is a detectable moiety; and M is a connecting group, wherein m is an integer ranging from 0 to about 20.

In another embodiment; A is H or H₄O₉P₃—; X is O; Y is H or OR₉, wherein R₉ is hydrogen, alkyl or aryl; Z is hydrogen, N₃, F or OR₁₀, wherein R₁₀ is hydrogen, alkyl or aryl; and L is amido alkyl and M is -(M₁)_(a)-(M₂)_(b)- wherein a and b are independently integers from 0 to about 5 and the sun of a and b is not greater than 15.

In another embodiment, L is —(CH₂)_(n)C(O)NR₃—, wherein R₃ is hydrogen, alkyl or aryl and n is an integer ranging from about 1 to about 10; M₁ is —(CH₂)_(i)O— and M₂ is —(CH₂)_(j)NH—, wherein i and j are independently integers from 1 to about 5.

In another embodiment, Y is H or OH; 2Z is H or OH; -L is —CH₂C(O)NH—; M₁ is —(CH₂CH₂O)₃— and M₂ is —CH₂CH₂NH—; and Q is biotin or a carboxyfluorescein.

In another embodiment, Y is OH; Z is OH; -L-(M)_(m)- is —CH₂C(O)NH—(CH₂CH₂O)₃—CH₂CH₂NH—; and Q is biotin or Y is OH; Z is OH; -L-(M)_(m)- is —CH₂C(O)NH—(CH₂CH₂O)₃—CH₂CH₂NH—; Q is carboxyfluorescein.

In another embodiment, A is H or H₄O₉P₃—; X is O; Y is H or OR₉, wherein R₉ is hydrogen, alkyl or aryl; Z is hydrogen, N, F or OR₁₀, wherein R₁₀ is hydrogen, alkyl or aryl; and L is amido alkyl and M is -(M₁)_(a)-(M₂)_(b)-(M₃)_(c)-(M₄)_(d)- wherein a, b, c, and d are independently integers from 0 to about 5 and the sum of a, b, c, and d is not greater than 15.

In another embodiment, L is —(CH₂)_(n)C(O)NR₃—, wherein R₃ is hydrogen, alkyl or aryl and n is an integer ranging from about 1 to about 10; each M is independently —C(O)(CH₂)_(k)O—, —(CH₂)_(i)O— or —(CH₂)_(j)NH—, wherein i, j and k are independently integers from 1 to about 5.

In another embodiment, L is —CH₂C(O)NR₃—, wherein R₃ is hydrogen or, alkyl; M₁ is —(CH₂)₂NH—, M₂ is —C(O)(CH₂)₂O—, M₃ is —(CH₂CH₂O)₃— and M₄ is —(CH₂)₂)NH—.

In another embodiment, Y is OH; Z is OH; -L-(M)_(m)- is —CH₂C(O)NH—CH₂CH₂NH—C(O)CH₂CH₂O—(CH₂Cl₂O)₃—CH₂CH₂NH—; Q is biotin.

In another embodiment, Y is OH; Z is OH; -L-(M)_(m)- is —CH₂C(O)NH—CH₂CH₂NH—; m is 1; and Q is carboxyfluorescein.

In another embodiment, L is —(CH₂)₂C(O)NR₃—, wherein R₃ is hydrogen or, alkyl; M₁ is —(CH₂)₂NH—, M₂ is —C(O)(CH₂)₂O—, M₃ is —(CH₂CH₂O)₃— and M₄ is —(CH₂)₂NH—.

In another embodiment, Y is OH; Z is OH; -L-(M)_(m)- is —CH₂C(O)NH—CH₂CH₂NH—C(O)CH₂CH₂O—(CH₂CH₂O)₃—CH₂CH₂NH—; Q is biotin.

In another embodiment, Y is OH; Z is OH; -L-(M)_(m)- is —CH₂CH₂C(O)NH—CH₂CH₂NH—; m is 1; and Q is carboxyfluorescein.

In another embodiment, A is H or H₄O₉P₃—; X is O; Y is H or OR₉, wherein R₉ is hydrogen, alkyl or aryl; Z is hydrogen, N₃, F or OR₁₀, wherein R₁₀ is hydrogen, alkyl or aryl; and L is functionalized alkyl and M is -(M₁)_(a)-(M₂)_(b)-(M₃)_(c)-(M₂)_(d)- wherein a, b, c, and d are independently integers from 0 to about 5 and the sum of a, b, c, and d is not greater than 15.

In another embodiment, L is —(CH₂)_(n)O—, wherein n is an integer ranging from about 1 to about 10; each M is independently —C(O)(CH₂)_(k)O—, —(CH₂)_(i)O— or —(CH₂)_(j)NH—, wherein i, j and k are independently integers from 1 to about 5.

In another embodiment, L is —CH₂O—; M₁ is —(CH₂)₂NH—, M₂ is —C(O)(CH₂)₂O—, M₃ is —(CH₂CH₂O)₃— and M₄ is —(CH₂)₂NH—.

In another embodiment, Y is OH; Z is OH; -L-(M)_(m)- is —CH₂O—CH₂CH₂NH—C(O)(CH₂)₂O—(CH₂CH₂O)₃—CH₂CH₂NH—; Q is biotin or Y is OH; Z is OH; -L-(M)_(m)- is —CH₂O—CH₂CH₂NH—; m is 1; and Q is carboxyfluorescein.

In another embodiment, L is —(CH₂)_(n)NR₃—, wherein R₃ is hydrogen, alkyl or aryl and n is an integer ranging from about 1 to about 10; each M is independently —C(O)(CH₂)_(k)O—, —(CH₂)_(i)O— or —(CH₂)_(j)NH—, wherein i, j and k are independently integers from 1 to about 5.

In another embodiment, L is —(CH₂)₆NH—; MI is —(CH₂)₂NH—, M₂ is —C(O)(CH₂)₂O—, and M₃ is —(CH₂CH₂O)₃—. In another embodiment, Y is OH; Z is OH; -L-(M)_(m)- is —(CH₂)₆NH—C(O)(CH₂)₂O—(CH₂CH₂O)₃—CH₂CH₂NH—; and Q is biotin or Y is OH; Z is OH; L is —(CH₂)₆NH—; m is 0; and Q is carboxyfluorescein.

In another embodiment, A is H or H₄O₉P₃—; X is O; Y is H or OR₉, wherein R₉ is hydrogen, alkyl or aryl; Z is hydrogen, N₃, F or OR₁₀, wherein R₁₀ is hydrogen, alkyl or aryl; and L is alkenyl alkyl and M is -(M₁)_(a)-(M₂)_(b)-(M₃)_(c)-(M₄)_(d)- wherein a, b, c, and d are independently integers from 0 to about 5 and the sum of a, b, c, and d is not greater than 15.

In another embodiment, L is—structure —CH═CH—(CH₂)_(n)C(O)N(R₆)—, wherein R₆ is hydrogen, alkyl or aryl and n is in integer ranging from about 0 to about 10; each M is independently —C(O)(CH₂)_(k)O—, —(CH₂)_(i)O— or —(CH₂)_(j)NH—, wherein i, j and k are independently integers from 1 to about 5.

In another embodiment, L is —CH═C(H—C(O)N(H); M₁ is —(CH₂)₂NH—, M₂ is —C(O)(CH₂)₂O—, M₃ is —(CH₂CH₂O)₃— an M₄ is —(CH₂)₂NH—.

In another embodiment, Y is OH; Z is Oil; -L-(M)_(m)- is —CH═CH—C(O)NH—CH₂CH₂NH—C(O)(CH₂)₂O—(CH₂CH₂O)₃—CH₂CH₂NH—; Q is biotin or Y is OH; Z is OH; -L-(M)_(m)- is —CH═CH—C(O)NH—CH₂CH₂NH—; m is 1; and Q is carboxyfluorescein.

In another embodiment, the nucleic acid labeling compounds have the following structure:

wherein A is hydrogen or a functional group that permits the attachment of the nucleic acid labeling compound to a nucleic acid; L is a linker moiety; Q is a detectable moiety; and M is a connecting group, wherein m is an integer ranging from 0 to about 3.

In another embodiment, A is H or H₄O₉P₃—; L is alkanoyl; and Q is biotin or a carboxyfluorescein; M is —NR₃— where R₃ is hydrogen or alkyl, and wherein m is 1 or 0.

In another embodiment, L is —C(O)(CH₂)_(n)— wherein n is an integer ranging from about 1 to about 10; M is —NH—; Q is biotin or a carboxyfluorescein.

In another embodiment, -L-(M)_(m)- is —C(O)(CH₂)₆—NH—; and Q is biotin or -L-(M)_(m)- is —C(O)(CH₂)₆—NH— and Q is carboxyfluorescein.

In another embodiment, the nucleic acid labeling compounds have the following structures:

wherein A is hydrogen or a functional group that permits the attachment of the nucleic acid labeling compound to a nucleic acid; X₁ is O, S, NR₁ or CHR₂, wherein R₁ and R₂ are, independently, hydrogen, alkyl or aril; R₁₅ is hydrogen, alkyl or aryl; Y₁ is hydrogen, N₃, F, OR₉, SR₉ or NHR₉, wherein R₉ is hydrogen, alkyl or aryl; Z₁ is hydrogen, N₃, F, OR₉, SR₉ or NHR₁₀, wherein R₁₀ is hydrogen, alkyl or aryl; wherein one of Y₁ or Z₁ is a group having the formula —X₂L-(M)_(m)-Q; X₂ is O, S, or NR₁₆, and R₁₆ is hydrogen, alkyl or aryl; L is a linker moiety; Q is a detectable moiety; and M is a connecting group, wherein m is an integer ranging from 0 to about 20.

In another embodiment, A is H or H₄O₉P₃—; X₁ is O; Y₁ is hydrogen, OR₉, wherein R₉ is hydrogen, or alkyl, or —NR₁₆-(M)_(m)-Q; wherein R₁₆ is hydrogen, alkyl or aryl; Z₁ is hydrogen OR₁₀, wherein R₁₀ is hydrogen, or alkyl, or —NR₁₆-L-(M)_(m)-Q, wherein R₁₆ is hydrogen, or alkyl; L is N-alkyl amido; R₁₅ is hydrogen or alkyl; M is —(CH₂)_(n)NR₃— where R₃ is hydrogen or alkyl, and m is from 1 to about 15.

In another embodiment, Y₁ is hydrogen or OH; Z₁ is —NH-L-(M)_(m)-Q; L is —(CH₂)_(n)NHC(O)— where n is an integer from 1 to about 10; M is —NH(CH₂)_(p)— where p is an integer from 1 to about 10; R₁₅ is hydrogen or methyl; and Q is biotin or a carboxyfluorescein.

In another embodiment, Y₁ is OH; R₁₅ is hydrogen; -L-(M)_(m)- is —(CH₂)₄NH—C(O)(CH₂)₅NH—; and Q is biotin.

In another embodiment, Y₁ is OH; R₁₅ is hydrogen; -L-(M)_(m)- is —(CH₂)₄NH—C(O)(CH₂)₅NH—; and Q is a carboxyfluorescein.

In another embodiment, Y₁ is OH; 115 is methyl; -L-(M)_(m)- is —(CH₂)₄NH—C(O)(CH₂)₅NH—; and Q is biotin.

In another embodiment, Y₁ is OH; R₁₅ is methyl; -L-(M)_(m)- is —(CH₂)₄NH—C(O)(CH₂)₅NH—; and Q is a carboxyfluorescein.

In another embodiment, Y₁ is —NH-L-(M)_(m)-Q; Z₁ is hydrogen or OH; L is —(CH₂)_(n)NHC(O)— where n is an integer from 1 to about 10; M is —NH(CH₂)_(p)— where n is an integer from 1 to about 10; R₁₅ is hydrogen or methyl; and Q is biotin or a carboxyfluorescein.

In another embodiment, Z₁ is OH; R₁₅ is hydrogen; -L-(M)_(m)- is —(CH₂)₄NH—C(O)(CH₂)₅NH—; and Q is biotin.

In another embodiment, of the nucleic acid labeling compound, Z₁ is OH; R₁₅ is hydrogen; -L-(M)_(m)- is —(CH₂)₄NH—C(O)(CH₂)₅NH—; and Q is a carboxyfluorescein.

In another embodiment, Z₁ is OH; R₁₅ is methyl; -L-(M)_(m)- is —(CH₂)₄NH—C(O)(CH₂)₅NH—; and Q is biotin.

In another embodiment, Z₁ is OH; R₁₅ is methyl; -L-(M)_(m)- is —(CH₂)₄NH—C(O)(CH₂)₅NH—; and Q is a carboxyfluorescein.

In another embodiment, A is H or H₄O₉P₃—; X₁ is O; Y₁ is hydrogen, OR₉, wherein R₉ is hydrogen, or alkyl, or —O-L-(M)_(m)-Q; Z₁ is hydrogen OR₁₀, wherein R₁₀ is hydrogen, or alkyl, or —O-L-(M)_(m)-Q, or alkyl; L is alkylene; and m is from 1 to about 10.

In another embodiment, Y₁ is hydrogen or OH; Z₁ is —O-L-(M)_(m)-Q; L is —(CH₂)_(n)— where n is an integer from 1 to about 12; M is —NH—R₁₅ is hydrogen or methyl; and Q is biotin or a carboxyfluorescein.

In another embodiment, Y₁ is OH; R₁₅ is hydrogen; -L-(M)_(m)- is —(CH₂)₆—NH—; and Q is biotin.

In another embodiment wherein Y₁ is OH; R₁₅ is hydrogen; -L-(M)_(m)- is —(CH₂)₆—NH—; and Q is a carboxyfluorescein.

In another embodiment, Y₁ is OH; R₁₅ is methyl; -L-(M)_(m)- is —(CH₂)₆—NH—; and Q is biotin.

In another embodiment, Y₁ is OH; R₁₅ is methyl; -L-(M)_(m)- is —(CH₂)₆—NH—; and Q is a carboxyfluorescein.

In another embodiment, Y₁ is —O-L-(M)_(m)-Q; Z₁ is hydrogen or OH; L is —(CH₂)_(n)— where n is an integer from 1 to about 12; M is —NH—; R₁₅ is hydrogen or methyl; and Q is biotin or a carboxyfluorescein.

In another embodiment, Z₁ is OH; R₁₅ is hydrogen; -L-(M)_(m)- is —(CH₂)₆—NH—; and Q is biotin.

In another embodiment, Z₁ is OH; R₁₅ is hydrogen; -L-(M)_(m)- is —(CH₂)₆—NH—; and Q is a carboxyfluorescein.

In another embodiment, Z₁ is OH; R₁₅ methyl; -L-(M)_(m)- is —(CH₂)₆—NH—; and Q is biotin.

In another embodiment, Z₁ is OH; R₁₅ is methyl; -L-(M)_(m)- is —(CH₂)₆—NH—; and Q is a carboxyfluorescein.

In another embodiment, A is H or H₄O₉P₃—; X₁ is O; Y₁ is hydrogen, OR₉, wherein R₉ is hydrogen, or alkyl, or —S-L-(M)_(m)-Q; Z₁ is hydrogen OR₁₀, wherein R₁₀ is hydrogen, or alkyl, or —S-L-(M)_(m)-Q; L is alkylene; X₂ is S; and m is from 1 to about 10.

In another embodiment, Y₁ is hydrogen or OH; Z₁ is —S-L-(M)_(m)-Q; L is —S—(CH₂)_(n)— where n is an integer from 1 to about 10; M is —NH—; R₁₅ is hydrogen or methyl; and Q is biotin or a carboxyfluorescein.

In another embodiment, Y₁ is OH; R₁₅ is hydrogen; -L-(M)_(m)- is —S—(CH₂)₂—NH—; and Q is biotin.

In another embodiment, Y₁ is OH; R₁₅ is hydrogen; -L-(M)_(m)- is —S—(CH₂)₂—NH—; and Q is a carboxyfluorescein.

In another embodiment, Y₁ is OH; R₁₅ is methyl; -L-(M)_(m)- is —S—(CH₂)₂—NH—; and Q is biotin.

In another embodiment, Y₁ is OH, R₁₅ is methyl; -L-(M)_(m)- is —S—(CH₂)₂—NH—; and Q is a carboxyfluorescein.

In another embodiment, Y₁ is —S-L-(M)_(m)-Q; Z₁ is hydrogen or OH; L is —S—(CH₂)_(n)— where n is an integer from 1 to about 10; M is —NH—; R₁₅ is hydrogen or methyl; and Q is biotin or a carboxyfluorescein.

In another embodiment, Z₁ is OH; R₁₅ is hydrogen; -L-(M)_(m)- is —S—(CH₂)₂—NH—; and Q is biotin.

In another embodiment, Z₁ is OH; R₁₅ is hydrogen; -L-(M)_(m)- is —S—(CH₂)₂—NH—; and Q is a carboxyfluorescein.

In another embodiment, Z₁ is OH; R₁₅ is methyl; -L-(M)_(m)- is —S—(CH₂)₂—NH—; and Q is biotin.

In another embodiment, Z₁ is OH; R₁₅ is methyl; -L-(M)_(m)- is —S—(CH₂)₂—NH—; and Q is a carboxyfluorescein.

In another embodiment, the nucleic acid labeling compounds have the following structure:

wherein A is hydrogen or a functional group that permits the attachment of the nucleic acid labeling compound to a nucleic acid; X₁ is O, S, NR₁ or CHR₂, wherein R₁ and R₂ are, independently, hydrogen, alkyl or aryl; X₂ is a bond or alkylene; Q is a detectable moiety; and G is -L-(M)_(m)- where L is a linker moiety and each M a connecting group, where m is from 0 to about 20.

In another embodiment, A is H or H₄O₉P₃—; X₁ is O; X₂ is a bond; and G is —C(O)NR₃—(CH₂)_(m)—(CH₂CH₂O)_(n)—CH₂CH₂—C(O)NR₃—, where R₃ is hydrogen or alkyl, and m and n are independently an integer from 1 to about 15.

In another embodiment, G is —C(O)NH—(CH₂)_(m)—(CH₂CH₂O)_(n)—CH₂CH₂—C(O)NH—

where m is from 1 to about 6 and n is from 1 to about 4. Preferably, n is 3 or 4 and m is 5 or 6.

In another embodiment, A is H or H₄O₉P₃—; X₁ is O; X₂ is CH₂; and G is —C(O)NR₃—(CH₂)_(m)—(CH₂CH₂O)_(n)—CH₂CH₂—C(O)NR₃—, where R₃ is hydrogen or alkyl, and m and n are independently an integer from 1 to about 15.

In another embodiment, A is H or H₄O₉P₃—; X₁ is O; X₂ is CH₂; and G is —C(O)NR₃—(CH₂), —(CH₂CH₂O)_(n)—CH₂CH₂—C(O)NR₃—, where R₃ is hydrogen or alkyl, and m and n are independently an integer from 1 to about 15.

The present invention also provides nucleic acid derivatives produced by coupling a nucleic acid labeling compound with a nucleic acid and hybridization products comprising the nucleic acid derivatives bound to a complementary probe.

The present invention also provides nucleic acid derivatives produced by coupling one of the nucleic acid labeling compounds of the invention with a nucleic acid and the hybridization products comprising the nucleic acid derivatives bound to a complementary probe. The hybridization product formed from the nucleic acid derivatives comprise the nucleic acid derivative bound to a complementary probe. In one embodiment, the probe is attached to a glass chip.

The present invention also provides methods of synthesizing nucleic acid derivatives by attaching a nucleic acid labeling compound to a nucleic acid. It further provides methods of detecting nucleic acids involving incubating the nucleic acid derivatives with a probe.

In yet another embodiment, the methods involve the steps of: (a) providing at least one nucleic acid coupled to a support; (b) providing a labeled moiety capable of being coupled with a terminal transferase to said nucleic acid; (c) providing said terminal transferase; and (d) coupling said labeled moiety to said nucleic acid using said terminal transferase.

In still another embodiment, the methods involve the steps of: (a) providing at least two nucleic acids coupled to a support; (b) increasing the number of monomer units of said nucleic acids to form a common nucleic acid tail on said at least two nucleic acids; (c) providing a labeled moiety capable of recognizing said common nucleic acid tails; and (d) contacting said common nucleic acid tails and said labeled moiety.

In still yet another embodiment, the methods involve the steps of: (a) providing at least one nucleic acid coupled to a support; (b) providing a labeled moiety capable of being coupled with a ligase to said nucleic acid; (c) providing said ligase; and (d) coupling said labeled moiety to said nucleic acid using said ligase.

This invention also provides compounds of the formulas described herein.

DEFINITIONS

The following definitions are used, unless otherwise described. Halo is fluoro, chloro, bromo, or iodo. Alkyl, alkoxy, aralkyl, alkylaryl, etc. denote both straight and branched alkyl groups; but reference to an individual radical such as “propyl” embraces only the straight chain radical, a branched chain isomer such as “isopropyl” being specifically referred to. Aryl includes a phenyl radical or an ortho-fused bicyclic carbocyclic radical having about nine to ten ring atoms in which at least one ring is aromatic. Heteroaryl encompasses a radical attached via a ring carbon of a monocyclic aromatic ring containing five or six ring atoms consisting of carbon and one to four heteroatoms each selected from the group consisting of non-peroxide oxygen, sulfur, and N(X) wherein X is absent or is H, O, (C₁-C₄)alkyl, phenyl or benzyl, as well as a radical of an ortho-fused bicyclic heterocycle of about eight to ten ring atoms derived therefrom, particularly a benz-derivative or one derived by fusing a propylene, trimethylene, or tetramethylene diradical thereto.

“Alkyl” refers to a straight chain, branched or cyclic chemical groups containing only carbon and hydrogen. Alkyl groups include, without limitation, ethyl, propyl, butyl, pentyl, cyclopentyl and 2-methylbutyl. Alkyl groups are unsubstituted or substituted with 1 or more substituents (e.g., halogen, alkoxy, amino).

“Alkylene” refers to a straight chain, branched or cyclic chemical group containing only carbon and hydrogen. Alkyl groups include, without limitation, ethylene, propylene, butylene, pentylene, and 2-methylbutylene. Alkyl groups are unsubstituted or substituted with 1 or more substituents (e.g., halogen, alkoxy, amino).

“Aryl” refers to a monovalent, unsaturated aromatic carbocyclic group. Aryl groups include, without limitation, phenyl, naphthyl, anthryl and biphenyl. Aryl groups are unsubstituted or substituted with 1 or more substituents (e.g. halogen, alkoxy, amino). “Arylene” refers to a divalent aryl group.

“Amido” refers to a chemical group having the structure —C(O)NR₃—, wherein R₃ is hydrogen, alkyl or aryl. Preferably, the amido group is of the structure —C(O)NR₃— where R3 is hydrogen or alkyl having from about 1 to about 6 carbon atoms. More preferably, the amido alkyl group is of the structure —C(O)NH—.

“Alkanoyl” refers to a chemical group having the structure —(CH₂)_(n)C(O)—, n is an integer ranging from 0 to about 10. Preferably, the alkanoyl group is of the structure —(CH₂)_(r)C(O)—, wherein n is an integer ranging from about 2 to about 10. More preferably, the alkanoyl group is of the structure —(CH₂)_(n)C(O)—, wherein n is an integer ranging from about 2 to about 6. Most preferably, the alkanoyl group is of the structure —CH₂C(O)—.

“Alkyl amido” refers to a chemical group having the structure —R₄C(O)NR₃—, wherein R₃ is hydrogen, alkyl or aryl, and R₄ is alkylene or arylene. Preferably, the alkyl amido group is of the structure —(CH₂)_(n)C(O)NH—, wherein n is an integer ranging from about 1 to about 10. More preferably, n is an integer ranging from about 1 to about 6. Most preferably, the alkyl amido group has the structure —(CH₂)₂C(O)NH— or the structure —CH₂C(O)NH—.

“N-Amido alkyl” refers to a chemical group having the structure —C(O)NR₃R₄—, wherein R₃ is hydrogen, alkyl or aryl, and R₄ is alkylene or arylene. Preferably, the N-amido alkyl group is of the structure —C(O)NH(CH₂)_(n)R₅—, wherein n is an integer ranging from about 2 to about 10, and R₅ is O, NR₆, or C(O), and wherein R₆ is hydrogen, alkyl or aryl. More preferably, the N-amido alkyl group is of the structure —C(O)NH(CH₂)_(n)N(H)—, wherein n is an integer ranging from about 2 to about 6. Most preferably, the N-amido alkyl group is of the structure —C(O)NH(CH₂)₄N(H)—.

“Alkynyl alkyl” refers to a chemical group having the structure —C≡C—R₄—, wherein R₄ is alkyl or aryl. Preferably, the alkynyl alkyl group is of the structure —C≡C—(CH₂)_(n)R₅—, wherein n is an integer ranging from 1 to about 10, and R₅ is O, NR₆ or C(O), wherein R₆ is hydrogen, alkyl or aryl. More preferably, the alkynyl alkyl group is of the structure —C≡C—(CH₂)_(n)N(H)—, wherein n is an integer ranging from 1 to about 4. Most preferably, the alkynyl alkyl group is of the structure —C≡C—CH₂N(H)—.

“Alkenyl alkyl” refers to a chemical group having the structure —CH═CH—R₄—, wherein R₄ is a bond, alkyl or aryl. Preferably, the alkenyl alkyl group is of the structure —CH═CH—(CH₂)_(n)R₅—, wherein n is an integer ranging from 0 to about 10, and R₅ is O, NR₆, C(O) or C(O)NR₆, wherein R₆ is hydrogen, alkyl or aryl. More preferably, the alkenyl alkyl group is of the structure —CH═CH—(CH₂)_(n)C(O)NR₆—, wherein n is an integer ranging from 0 to about 4. Most preferably, the alkenyl alkyl group is of the structure —CH═CH—C(O)N(H)—.

“Functionalized alkyl” refers to a chemical group of the structure —(CH₂)_(n)R₇—, wherein n is an integer ranging from 1 to about 10, and R₇ is O, S, NH or C(O). Preferably, the functionalized alkyl group is of the structure —(CH₂)_(n)C(O)—, wherein n is an integer ranging from 1 to about 4. More preferably, the functionalized alkyl group is of the structure —CH₂C(O)—.

“Alkoxy” refers to a chemical group of the structure —O(CH₂)_(n)R₈—, wherein n is an integer ranging from 2 to about 10, and R₈ is a bond, O, S, NH or C(O). Preferably, the alkoxy group is of the structure —O(CH₂)_(n)— wherein n is an integer ranging from 2 to about 4. More preferably, the alkoxy group is of the structure —OCH₂CH₂—.

“Alkyl thio” refers to a chemical group of the structure —S(CH₂)_(n)R₈—, wherein n is an integer ranging from 1 to about 10, and R₈ is a bond, O, S, NH or C(O). Preferably, the alkyl thio group is of the structure —S(CH₂)_(n)—, wherein n is an integer ranging from 2 to about 4. More preferably, the thio group is of the structure —SCH₂CH₂C(O)—.

“Amino alkyl” refers to a chemical group having an amino group attached to an alkyl group. Preferably an amino alkyl is of the structure —(CH₂)_(n)NH—, wherein n is an integer ranging from about 2 to about 10. More preferably it is of the structure —(CH₂)_(n)NH—, wherein n is an integer ranging from about 2 to about 4. Most preferably, the amino alkyl group is of the structure —(CH₂)₂NH—.

“Nucleic acid” refers to a polymer comprising 2 or more nucleotides and includes single-, double- and triple stranded polymers. “Nucleotide” refers to both naturally occurring and non-naturally occulting compounds and comprises a heterocyclic base, a sugar, and a linking group, preferably a phosphate ester. For example, structural groups may be added to the ribosyl or deoxyribosyl unit of the nucleotide, such as a methyl or allyl group at the 2′-O position or a fluoro group that substitutes for the 2′-O group. The linking group, such as a phosphodiester, of the nucleic acid may be substituted or modified, for example with methyl phosphonates or O-methyl phosphates. Bases and sugars can also be modified, as is known in the art. “Nucleic acid,” for the purposes of this disclosure, also includes “peptide nucleic acids” in which native or modified nucleic acid bases are attached to a polyamide backbone.

The phrase “coupled to a support” means bound directly or indirectly thereto including attachment by covalent binding, hydrogen bonding, ionic interaction, hydrophobic interaction, or otherwise.

“Probe” refers to a nucleic acid that can be used to detect, by hybridization, a target nucleic acid. Preferably, the probe is complementary to the target nucleic acid along the entire length of the probe, but hybridization can occur in the presence of one or more base mismatches between probe and target.

“Perfect match probe” refers to a probe that has a sequence that is perfectly complementary to a particular target sequence. The test probe is typically perfectly complementary to a portion (subsequence) of the target sequence. The perfect match (PM) probe can be a “test probe”, a “normalization control” probe, an expression level control probe and the like. A perfect match control or perfect match probe is, however, distinguished from a “mismatch control” or “mismatch probe.” In the case of expression monitoring arrays, perfect match probes are typically preselected (designed) to be complementary to particular sequences or subsequences of target nucleic acids (e.g., particular genes). In contrast, in generic difference screening arrays, the particular target sequences are typically unknown. In the latter case, prefect match probes cannot be preselected. The term perfect match probe in this context is to distinguish that probe from a corresponding “mismatch control” that differs from the perfect match in one or more particular preselected nucleotides as described below.

“Mismatch control” or “mismatch probe”, in expression monitoring arrays, refers to probes whose sequence is deliberately selected not to be perfectly complementary to a particular target sequence. For each mismatch (MM) control in a high-density array there preferably exists a corresponding perfect match (PM) probe that is perfectly complementary to the same particular target sequence. In “generic” (e.g., random, arbitrary, haphazard, etc.) arrays, since the target nucleic acid(s) are unknown perfect match and mismatch probes cannot be a priori determined, designed, or selected. In this instance, the probes are preferably provided as pairs where each pair of probes differ in one or more preselected nucleotides. Thus, while it is not known a priori which of the probes in the pair is the perfect match, it is known that when one probe specifically hybridizes to a particular target sequence, the other probe of the pair will act as a mismatch control for that target sequence. It will be appreciated that the perfect match and mismatch probes need not be provided as pairs, but may be provided as larger collections (e.g., 3. 4, 5, or more) of probes that differ from each other in particular preselected nucleotides. While the mismatch(s) may be located anywhere in the mismatch probe, terminal mismatches are less desirable as a terminal mismatch is less likely to prevent hybridization of the target sequence. In a particularly preferred embodiment, the mismatch is located at or near the center of the probe such that the mismatch is most likely to destabilize the duplex with the target sequence under the test hybridization conditions. In a particularly preferred embodiment, perfect matches differ from mismatch controls in a single centrally-located nucleotide.

“Labeled moiety” refers to a moiety capable of being detected by the various methods discussed herein or known in the art.

Nucleic Acid Labeling Compounds

The nucleic acid labeling compounds of the present invention are of the following structure: A-O—CH₂-T-H_(c)-L-(M)_(m)-Q, or A-O—CH₂-T(H_(c))-L-(M)_(m)-Q, or A-O—CH₂-T-Q

wherein A is hydrogen or a functional group that permits the attachment of the nucleic acid labeling compound to a nucleic acid; T is an optional template moiety; H_(c) is an heterocyclic group; L is a linker moiety; Q is a detectable moiety; and M is an connecting group, wherein m is an integer ranging from 0 to about 20. In a preferred embodiment m is from 0 to about 15. In a more preferred embodiment m is from 0 to about 10. In the most preferred embodiment in is from 0 to about 5.

The group A is either hydrogen or a functional group that permits the attachment of a nucleic acid labeling compound to a nucleic acid. Nonlimiting examples of such groups include the following: monophosphate; diphosphate; triphosphate (H₄O₉P); phosphoramidite ((R₂N)(R′O)P), wherein R is linear, branched or cyclic alkyl, and R′ is a protecting group such as 2-cyanoethyl; and H-phosphonate (HP(O)O—HNR₃), wherein R is linear, branched or cyclic alkyl.

The template moiety (T) is covalently attached to a methylene group (CH₂) at one position and a heterocyclic group (H_(c)) or the linker moiety at another position. A nonlimiting set of template moieties is shown in FIG. 1, wherein the substituents are defined as follows: X is O, S, NR₁ or CHR₂; Y is H, N₃, F, OR₉, SR₉ or NHR₉; Z is H, N₃, F or OR₁₀; W is O, S, or CH₂; D is O, or S; and, G is O, NH or CH₂. The substituents R₁, R₂, R₉ and R₁₀ are independent of one another and are H, alkyl or aryl.

The heterocyclic group (H_(c)) is a cyclic moiety containing both carbon and a heteroatom.

The linker moiety (L) of the nucleic acid labeling compound is covalently bound to the heterocycle (H_(c)) or the template moiety at one terminal position. It is attached to the detectable moiety (Q) at another terminal position, either directly or through a connecting group (M). It is of a structure that is sterically and electronically suitable for incorporation into a nucleic acid. Linker moieties are amido alkyl groups, functionalized alkyl groups, alkenyl alkyl groups, alkanoyl groups, and N-alkyl amido groups.

Amido groups have the structure —C(O)NR₃—, wherein R₃ is hydrogen, alkyl or aryl. Preferably, the amido group is of the structure —C(O)NR₃— where R₃ is hydrogen or alkyl having from about 1 to about 6 carbon atoms. More preferably, the amido alkyl group is of the structure —C(O)NH—.

Alkanoyl groups have the structure —(CH₂)_(n)C(O)—, n is an integer ranging from 0 to about 10. Preferably, the alkanoyl group is of the structure —(CH₂)_(n)C(O)—, wherein n is an integer ranging from about 2 to about 10. More preferably, the alkanoyl group is of the structure —(CH₂)_(n)C(O)—, wherein n is an integer ranging from about 2 to about 6. Most preferably, the alkanoyl group is of the structure —CH₂C(O)—.

Amido alkyl groups have the structure —R₄C(O)NR₃—, wherein R₃ is hydrogen, alkyl or aryl, and R₄ is alkyl or aryl. The amido alkyl group is preferably of the structure —(CH₂)_(n)C(O)NH—, wherein n is an integer ranging from about 1 to about 10. More preferably, n is an integer ranging from about 1 to about 6. Most preferably, the alkyl amido group has the structure —(CH₂)₂C(O)NH— or the structure —CH₂C(O)NH—.

N-Amido alkyl groups have the structure —C(O)NR₃R₄—, wherein R₃ is hydrogen, alkyl or aryl, and R₄ is alkylene or arylene. Preferably, the N-amido alkyl group is of the structure —C(O)NH(CH₂)_(n)R₅—, wherein n is an integer ranging from about 2 to about 10, and R₅ is O, NR₆, or C(O), and wherein R₆ is hydrogen, alkyl or aryl. More preferably, the N-amido alkyl group is of the structure —C(O)NH(CH₂)_(n)N(H)—, wherein n is an integer ranging from about 2 to about 6. Most preferably, the N-amido alkyl group is of the structure —C(O)NH(CH₂)₄N(H)—.

Alkenyl alkyl groups are of the structure —CH═CH—R₄—, wherein R₄ is alkyl or aryl. The alkenyl group is preferably of the structure —CH═CH(CH₂)_(n)R₅—, wherein n is an integer ranging from 1 to about 10, and R₅ is O, NR₆, C(O) or C(O)NR₆, wherein R₆ is hydrogen, alkyl or aryl. More preferably, the alkenyl alkyl group is of the structure —CH═CH—(CH₂)_(n)C(O)NR₆—, wherein n is an integer ranging from 0 to about 4. Most preferably, the alkenyl alkyl group is of the stricture —CH═CH—C(O)N(H)—.

Functionalized alkyl groups are of the structure —(CH₂)_(n)R₇—, wherein n is an integer ranging from 1 to about 10, and R₇ is CO, S, NH, or C(O). The functionalized alkyl group is preferably of the structure —(CH₂)_(n)C(O)—, wherein n is an integer ranging from 1 to about 4. More preferably, the functionalized alkyl group is —CH₂C(O)—.

Alkoxy groups are of the structure —O(CH₂)_(n)R₈—, wherein n is an integer ranging from 2 to about 10, and R₈ is O, S, NH, or C(O). The alkoxy group is preferably of the structure —O(CH₂)_(n)— or —O(CH₂)_(n)C(O)—, wherein n is an integer ranging from 2 to about 4. More preferably, the alkoxy group is of the structure —OCH₂CH₂— or —OCH₂Cl₂C(O)—.

Alkyl thio groups are of the structure —S(CH₂)_(n)R₈—, wherein n is an integer ranging from 2 to about 10, and R₈ is O, S, NIT, or (C(O). The alkyl thio group is preferably of the structure —S(CH₂)_(n)C(O)—, wherein n is an integer ranging from 2 to about 4. More preferably, the alkyl thio group is of the structure —SCH₂CH₂C(O)—.

Amino alkyl groups comprise an amino group attached to an alkyl group. Preferably, amino alkyl groups are of the structure —NH(CH₂)_(n)NH—, wherein n is an integer ranging from about 2 to about 110. The amino alkyl group is more preferably of the structure —(CH₂)_(n)NH—, wherein n is an integer ranging from about 2 to about 4. Most preferably, the amino alkyl group is of the structure —(CH₂)₄NH—.

The detectable moiety (Q) is a chemical group that provides an signal. The signal is detectable by any suitable means, including spectroscopic, photochemical, biochemical, immunochemical, electrical, optical or chemical means. In certain cases, the signal is detectable by 2 or more means.

The detectable moiety provides the signal either directly or indirectly. A direct signal is produced where the labeling group spontaneously emits a signal, or generates a signal upon the introduction of a suitable stimulus. Radiolabels, such as ³H, ¹²⁵I, ³⁵S, ¹⁴C or ³²P, and magnetic particles, such as Dynabeads™, are nonlimiting examples of groups that directly and spontaneously provide a signal. Labeling groups that directly provide a signal in the presence of a stimulus include the following nonlimiting examples: colloidal gold (40-80 nm diameter), which scatters green light with high efficiency; fluorescent labels, such as fluorescein, texas red, rhodamine, and green fluorescent protein (Molecular Probes, Eugene, Oreg.), which absorb and subsequently emit light; chemiluminescent or bioluminescent labels, such as luminol, lophine, acridine salts and luciferins, which are electronically excited as the result of a chemical or biological reaction and subsequently emit light; spin labels, such as vanadium, copper, iron, manganese and nitroxide free radicals, which are detected by electron spin resonance (ESR) spectroscopy; dyes, such as quinoline dyes, triarylmethane dyes and acridine dyes, which absorb specific wavelengths of light; and colored glass or plastic (e.g., polystyrene, polypropylene, latex, etc.) beads. See U.S. Pat. Nos. 3,817,837; 3,850,752; 3,939,350; 3,996,345; 4,277,437; 4,275,149 and 4,366,241.

A detectable moiety provides an indirect signal where it interacts with a second compound that spontaneously emits a signal, or generates a signal upon the introduction of a suitable stimulus. Biotin, for example, produces a signal by forming a conjugate with streptavidin, which is then detected. See Hybridization With Nucleic Acid Probes. In Laboratory Techniques in Biochemistry and Molecular Biology; Tijssen, P., Ed.; Elsevier: N.Y., 1993; Vol. 24. An enzyme, such as horseradish peroxidase or alkaline phosphatase, that is attached to an antibody in a label-antibody-antibody as in an ELISA assay, also produces an indirect signal.

A preferred detectable moiety is t fluorescent group. Fluorescent groups typically produce a high signal to noise ratio, thereby providing increased resolution and sensitivity in a detection procedure. Preferably, the fluorescent group absorbs light with a wavelength above about 300 nm, more preferably above about 350 nm, and most preferably above about 400 nm. The wavelength of the light emitted by the fluorescent group is preferably above about 310 nm, more preferably above about 360 nm, and most preferably above about 41 nm.

The fluorescent detectable moiety is selected from a variety of structural classes, including the following nonlimiting examples: 1- and 2-aminonaphthalene, p,p′diaminostilbenes, pyrenes, quaternary phenanthridine salts, 9-aminoacridines, p,p′-diaminobenzophenone imines, anthracenes, oxacarbocyanine, marocyanine, 3-aminoequilenin, perylene, bisbenzoxazole, bis-p-oxazolyl benzene, 1,2-benzophenazin, retinol, bis-3-aminopridinium salts, hellebrigenin, tetracycline, sterophenol, benzimidazolyl phenylamine, 2-oxo-3-chromen, indole, xanthen, 7-hydroxycoumarin, phenoxazine, salicylate, strophanthidin, porphyrins, triarylmethanes, flavin, xanthene dyes (e.g., fluorescein and rhodamine dyes); cyanine dyes; 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene dyes and fluorescent proteins (e.g., green fluorescent protein, phycobiliprotein).

A number of fluorescent compounds are suitable for incorporation into the present invention. Nonlimiting examples of such compounds include the following: dansyl chloride; fluoresceins, such as 3,6-dihydroxy-9-phenylxanthhydrol; rhodamineisothiocyanate; N-phenyl-1-amino-8-sulfonatonaphthalene; N-phenyl-2-amino-6-sulfonatonaphthalene; 4-acetamido-4-isothiocyanatostilbene-2,2′-disulfonic acid; pyrene-3-sulfonic acid; 2-toluidinonapththalene-6-sulfonate; N-phenyl, N-methyl 2-aminonaphthalene-6-sulfonate; ethidium bromide, stebrine; auromine-0,2-(9′-anthroyl)palmitate; dansyl phosphatidylethanolamin; N,N′-dioctadecyl oxacarbocycanine; N,N′-dihexyl oxacarbocyanine; merocyanine, 4-(3′-pyrenyl)butryate; d-3-aminodesoxy-equilenin; 12-(9′-anthroyl)stearate; 2-methylanthracene; 9-vinylanthracene; 2,2′-(vinylene-p-phenylene)bisbenzoxazole; p-bis[2-(4-methyl-5-phenyl oxazolyl)]benzene; 6-dimethylamino-1,2-benzophenzin; retinol; bis(3′-aminopyridinium)-1,10-decandiyl diiodide; sulfonaphthylhydrazone of hellibrienin; chlorotetracycline; N-(7-dimethylamino-4-methyl-2-oxo-3-chromenyl)maleimide; N-[p-(2-benzimidazolyl)phenyl]maleimide; N-(4-fluoranthyl)maleimide; bis(homovanillic acid); resazarin; 4-chloro-7-nitro-2,1,3-benzooxadizole; merocyanine 540; resorufin; rose bengal and 2,4-diphenyl-3(2H)-furanone. Preferably, the fluorescent detectable moiety is a fluorescein or rhodamine dye.

Another preferred detectable moiety is colloidal gold. The colloidal gold particle is typically 40 to 80 nm in diameter. The colloidal gold may be attached to a labeling compound in a variety of ways. In one embodiment, the linker moiety of the nucleic acid labeling compound terminates in a thiol group (—SH), and the thiol group is directly bound to colloidal gold through a dative bond. See Mirkin et al. Nature 1996, 382, 607-609. In another embodiment, it is attached indirectly, for instance through the interaction between colloidal gold conjugates of antibiotin and a biotinylated labeling compound. The detection of the gold labeled compound may be enhanced through the use of a silver enhancement method. See Danscher et al. J. Histotech 1993, 16, 201-207.

The connecting groups (M)_(m) may serve to covalently attach the linker group (L) to the detectable moiety (Q). Each M group can be the same or different and can independently be any suitable structure that will not interfere with the function of the labeling compound. Nonlimiting examples of M groups include the following: amino alkyl, —CO(CH₂)₅NH—, —CO—, —NH—, —CO(O)—, —CO(NH)—, —(CH₂)_(i)O—, —(CH₂)_(j)NH—, —C(O)(CH₂)_(h)O—, —CO(CH₂)₅NHCO(CH₂)₅NH—, —NH(CH₂CH₂O)_(k)NH—, and —CO(CH₂)₅—; wherein, k is an integer from 1 to about 5, preferably k is 1 or 2; m is an integer ranging from 0 to about 5, preferably 0 to about 3; h, i and j are independently integers from 1 to about 5, preferably 1 to about 3.

Synthesis of Nucleic Acid Labeling Compounds

FIG. 2 illustrates a synthetic route to nucleic acid labeling compound, 4, starting from 2-amino-5-(β-D-ribofuranosyl)-4(1H)-pyrimidinone, 1. The hydroxy groups are protected as the trimethyl silylethers according to the procedure described in J. Antibiot. 1977, 30, 129. The N1 nitrogen atom is alkylated using a substituted iodoamide having a biotin label attached, according to the procedure described in Tetrahedron 1984, 40, 33. (PEO-iodoacetyl biotin can be purchased from Pierce Chemical Co.) The silyl protecting groups are removed, providing a compound having free alcohol groups using acetic acid in methanol. The product is converted into a 5′-triphosphate to afford labeled compound 4.

FIG. 3 illustrates a synthetic route to nucleic acid labeling compounds, 6 and 7, starting from 2-amino-5-(β-D-ribofuranosyl)-4(1H)-pyrimidinone, 1. The hydroxy groups are protected as the trimethyl silylethers according to the procedure described in J. Antibiot. 1977, 30, 129 The N1 nitrogen atom is alkylated according to the procedure described in Tetrahedron 1984, 40, 33, using ethyl iodoacetate. The ester is converted to amide, 5, using ethylene diamine. The biotin labeled compound is prepared by reacting amide, 5, with Biotin-dPEG4™-NHS (purchased from Quanta Biodesign). Alternatively, amide 5 is reacted with 5-carboxyfluorescein-NHS. The silyl protecting groups are removed to provide a compound having free alcohol groups, using acetic acid in methanol. The product is converted into a 5′-triphosphate using standard phosphorylation conditions to afford, respectively, nucleic acid labeling compounds 6 and 7.

FIG. 4 illustrates an alternate synthetic route to nucleic acid labeling compounds, 6 and 7, starting from 2-amino-5-(β-D-ribofuranosyl)-4(1H)-pyrimidinone, 1. The hydroxy groups are protected as acetyl esters using acetic anhydride in pyridine. The N1 nitrogen atom is alkylated according to the procedure described in Tetrahedron 1984, 40, 33, using ethyl iodoacetate. The ester is converted to amide, 8, using ethylene diamine. The biotin labeled compound is prepared by reacting amide, 8, with biotin-dPEG4™-NHS (purchased from Quanta Biodesign). Alternatively, amide 8 is reacted with 5-carboxyfluorescein-NHS. The silyl protecting groups are removed to provide a compound having free alcohol groups, using acetic acid in methanol. The product is converted into a 5′-triphosphate using standard phosphorylation conditions to afford, respectively, nucleic acid labeling compounds 6 and 7.

FIG. 5 illustrates a synthetic route to nucleic acid labeling compounds 10 and 11, starting from 2-amino-5-(β-D-ribofuranosyl)-4(1H)-pyrimidinone, 1. The hydroxy groups are protected as acetyl esters using acetic anhydride in pyridine. The N1 nitrogen atom is alkylated according to the procedure described in K. Muhlegger, et al. 1996, WO 96/28640, using methyl acrylate in triethyl amine. The ester, 8 is converted to amide, 9, using ethylene diamine. The biotin labeled compound is prepared by reacting amide, 9, with biotin-dPEG4™-NHS (purchased from Quanta Biodesign). Alternatively, amide 9 is reacted with 5-carboxyfluorescein-NHS. The product is converted into a 5′-triphosphate using standard phosphorylation conditions to afford, respectively, nucleic acid labeling compounds 10 and 11.

FIG. 6 illustrates a synthetic route to nucleic acid labeling compounds, 14 and 15, starting from 2-amino-5-(β-D-ribofuranosyl)-4(1H)-pyrimidinone, 1. The hydroxy groups are protected as acetyl esters using acetic anhydride in pyridine. The N1 nitrogen atom is alkylated according to the procedure described in Tet Lett 1995 36, 3261, using methyl propynoate. The ester, 12 is converted to amide, 9, using ethylene diamine. The biotin labeled compound is prepared by reacting amide, 9, with Biotin-dPEG4™-NHS (purchased from Quanta Biodesign). Alternatively, amide 9 is reacted with 5-carboxyfluorescein-NHS. The product is converted into a 5′-triphosphate using standard phosphorylation conditions to afford, respectively, nucleic acid labeling compounds 14 and 15.

FIG. 7 illustrates a synthetic route to nucleic acid labeling compounds, 17 and 18, starting from 2-amino-5-(β-D-ribofuranosyl)-4(1H)-pyrimidinone, 1. The hydroxy groups are protected as the trimethyl silylethers according to the procedure described in J. Antibiot. 1977, 30, 129. The NI nitrogen atom is alkylated, using 2-(2-chloromethoxy-ethyl)-isoindole-1,3-dione, according to the procedure described in Chemo 1985, 31, 151. The product, 16 is treated with hydrazine in ethanol to remove the protecting groups. The biotin labeled compound is prepared by reacting the ether-amine with biotin-dPEG4™-NHS (purchased from Quanta Biodesign) using standard conditions. Alternatively, the ether-amine is reacted with (Ac)₂Fl-NHS using standard conditions. The product is converted into a 5′-triphosphate using standard phosphorylation conditions to afford, respectively, nucleic acid labeling compounds 17 and 18.

FIG. 8 illustrates a synthetic route to nucleic acid labeling compounds, 20 and 21, starting from 2-amino-5-(β-D-ribofuranosyl)-4(1H)-pyrimidinone, 1. The hydroxy groups are protected as acetyl esters using acetic anhydride in pyridine. The N1 nitrogen atom is alkylated using (6-trifluoroacetamido)hexyl alcohol in the presence of triphenyl phosphane ((Ph)₃P), and diethylazodicarboxylate (DEAD), according to the procedure described in Brossette, T. et al., J. Org. Chem. 1999, 64, 5083 and Nuclesies, Nucleotides and Nucleic Acids 2000, 19, 867. The N1 nitrogen atom is alkylated using (6-trifluoroacetamido)hexyl alcohol according to the procedure described in J. Antibiot. 1977, 30, 129. The protecting groups are removed to provide a compound having free amine and alcohol groups, using ammonia in methanol. The biotin labeled compound is prepared by reacting the ether-amine With Biotin-dPEG4™-NHS (purchased from Quanta Biodesign) using standard conditions. Alternatively, the ether-amine is reacted with (Ac)₂Fl-NHS using standard conditions. The product is converted into a 5′-triphosphate using standard phosphorylation conditions to afford, respectively, nucleic acid labeling compounds 20 and 21.

FIG. 9 illustrates a synthetic route to nucleic acid labeling compounds, 23 and 24, starting from 2-amino-5-(β-D-ribofuranosyl)-4(1H)-pyrimidinone, 1. The hydroxy groups are protected as acetyl esters using acetic anhydride in pyridine. The N1 nitrogen atom is alkylated using 2-(6-iodo-hexyl)-isoindole-1,3-dione according to the procedure described in J. Antibiot. 1977, 30, 129. The product, 22 is treated with hydrazine in ethanol to remove the protecting groups. The biotin labeled compound is prepared by reacting the free amine with Biotin-dPEG4™-NHS (purchased from Quanta Biodesign) using standard conditions. Alternatively, the ether-amine is reacted with (Ac)₂Fl-NHS using standard conditions. The product is converted into a 5′-triphosphate using standard phosphorylation conditions to afford, respectively, nucleic acid labeling compounds 23 and 24.

FIG. 10 illustrates a synthetic route to nucleic acid labeling compounds, 36, starting from [1,4]Dioxan-2-one, Shahi, S. P., et al., J. Org. Chem. (1999), 64: 4509-11, Nishimura, T., et al., J. Org. Chem. 1999, 64 6750-55, Nishida, H., et al., J. Polym. Sci. 2000, 38: 1560-67; (2-Hydroxy-ethoxy)-acetic acid methyl ester, Kitano, M.; and Ohashi, N., EP 787728 A1 (1997), or a polymer thereof. Nishida H. at al. J. Polym. Sci., (2000), 38: 1560-67, 33. The compound is reacted with a diamine having a suitable linker moiety, e.g., a polyethylene oxide, alkylene, a combination there of and the like. The labeled compound is prepared by reacting the ether-amine with a suitable labeling compound using standard conditions. The product is converted into a 5′-triphosphate using standard phosphorylation condition to afford, respectively, nucleic compound 36.

Nucleic Acid Labeling

Nucleic acids can be isolated from a biological sample or synthesized, on a solid support or in solution for example, according to methods known to those of skill in the art. As used herein, there is no limitation on the length or source of the nucleic acid used in a labeling process. Exemplary methods of nucleic acid isolation and purification are described in Theory and Nucleic Acid Preparation. In Laboratory Techniques in Biochemistry and Molecular Biology: Hybridization With Nucleic Acid Probes; P. Tijssen, Ed.; Part I; Elsevier: N.Y., 1993. A preferred method of isolation involves an acid guanidinium-phenol-chloroform extraction followed by oligo dT column chromatography or (dT)n magnetic bead use. Sambrook et al. Molecular Cloning: A Laboratory Manual, 2nd ed.; Cold Spring Harbor Laboratory, 1989; Vols. 1-3; and Current Protocols in Molecular Biology; F. Ausubel et al. Eds.; Greene Publishing and Wiley Interscience: N.Y., 1987.

In certain cases, the nucleic acids are increased in quantity through amplification. Suitable amplification methods; include, but are not limited to, the following examples: polymerase chain reaction (PCR) (Innis, et al. PCR Protocols. A guide to Methods and Application; Academic Press: San Diego, 1990); ligase chain reaction (LCR) (Wu and Wallace. Genomics 1989, 4, 560; Landgren, et al. Science 1988, 241, 1077; and Barringer, et al. Gene 1990, 89, 117); transcription amplification (Kwoh et al. Proc. Natl. Acad. Sci. USA 1989, 86, 1173); and self-sustained sequence replication (Guatelli, et al. Proc. Nat. Acad. Sci. USA 1990, 87, 1874).

The nucleic acid labeling compound can be incorporated into a nucleic acid using a number of methods. For example, it can be directly attached to an original nucleic acid sample (e.g., mRNA, polyA mRNA, c DNA) or to an amplification product. Methods of attaching a labeling compound to a nucleic acid include, without limitation, nick translation, 3-end-labeling, ligation, in vitro transcription (IVT) or random priming. Where the nucleic acid is an RNA, a labeled riboligonucleotide is ligated, for example, using an RNA ligase such asT4 RNA Ligase In The Enzymes; Uhlenbeck and Greensport, Eds.; Vol. XV, Part B, pp. 31-58; and, Sambrook et al., pp. 5.66-5.69. Terminal transferase is used to add deoxy-, dideoxy- or ribonucleoside triphosphates (dNTPs, ddNTPs or NTPs), for example, where the nucleic acid is single stranded DNA.

The labeling compound can also be incorporated at an internal position of a nucleic acid. For example, PCR in the presence of a labeling compound provides internally labeled amplification product. See, e.g., Yu et al. Nucleic Acids Research 1994, 22, 3226-3232. Similarly, IVT in the presence of a labeling compound can provide an internally labeled nucleic acid.

Probe Hybridization

The nucleic acid to which the labeling compound is attached can be detected after hybridization with a nucleic acid probe. Alternatively, the probe can be labeled, depending upon the experimental scheme preferred by the user. The probe is a nucleic acid, or a modified nucleic acid, that is either attached to a solid support or is in solution. It is complementary in structure to the labeled nucleic acid with which it hybridizes. The solid support is of any suitable material, including polystyrene based beads and glass chips. In a preferred embodiment, the probe or target nucleic acid is attached to a glass chip, such as a GeneChip® product (Affymetrix, Inc., Santa Clara, Calif.). See International Publication Nos. WO 97/10365, WO 97/29212, WO 97/27317, WO 95/11995, WO 90/15070, and U.S. Pat. Nos. 5,744,305 and 5,445,934 which are hereby incorporated by reference.

Because probe hybridization is often a step in the detection of a nucleic acid, the nucleic acid labeling compound must be of a structure that does not substantially interfere with that process. The steric and electronic nature of the labeling compound, therefore, is compatible with the binding of the attached nucleic acid to a complementary structure.

EXAMPLES

The following examples are offered to illustrate, but not to limit, the present invention.

General Experimental Details

Reagents were purchased from Aldrich Chemical Company (Milwaukee, Wis.) in the highest available purity. All listed solvents were anhydrous. Intermediates were characterized by ¹H NMR and mass spectrometry.

Example 1 Synthesis of fluorescein derivatives of 2′-amino-2′-deoxyuridine triphosphate and 3′-amino-3′-deoxythymidinetriphosphate (Scheme 1)

To 0.5 umoles (50 uL of a 10 mM solution) of the amino nucleotide triphosphate (1 or 2) in a 0.5 ml ependorf tube was added 25 ul of a 1 M aqueous solution of sodium borate, pH 8, 87 uL of methanol, and 88 uL (10 umol, 20 equiv) of a 100 mM solution of 5-carboxyfluorescein -X-NHS ester in methanol. The mixture was vortexed briefly and allowed to stand at room temperature in the dark for 15 hours. The sample was then purified by ion-exchange HPLC to afford the fluoresceinated derivatives 3 or 4 in about 78-84% yield. Relative efficiencies of incorporation of these compounds by TdT are shown in Table 1.

TABLE 1 Incorporation of triphosphate compounds by TdT.

TdT Labeling Efficiencies % Labeled X (3′) Y (2′) B (1′b) 40 U 160 U OH H uracil 100.0 100.0 NH2 H thymine 100 100 NHCO(CH2)5NH— H thymine 1.3 2.2 (CO-FL) OH NH2 uradil 65 95 OH NHCO(CH2)5NH—(CO-FL) uracil 3.0 6.6 OH O(CH2)6NH—(CO-FL) uracil 2.5 7.0 OH O(CH2)6NHCO—(CH2)5— uracil 15.0 17.0 NHCO-Biotin OH NH(CH2)5CH3 uracil 4.5 5.0

Example 2 Synthesis of N1-Labeled 2-Amino-5-(β-D-ribofuranosyl)-4(1H)-pyrimidinone

Synthesis of the N1-labeled 2-amino-5-(β-D-ribofuranosyl)-4(1H)-pyrimidinone, 55, involved alkylation at N1 using (conditions similar to those described by Muehlegger, et al. (WO 96/28640) for the N1-alkylation of pyrazalo-[4,3-d]pyrimidines (FIG. 3A).

Example 3 Synthesis of N-(6-(fluorescein-5-carboxamido)hexanoyl)-morpholino uridine triphosphate (Scheme 2)

Morpholino-uracil tosylate salt 25 (30 mg) was co-evaporated with pyridine (3×3 ml) and dissolved in 2 ml of pyridine and cooled to 0° C. Trifluoroacetic anhydride (30 uL) was added and stirred for 1 hour. The reaction was followed by HPLC until complete. The pyridine was removed and the residue was dissolved in 1 ml of water and filtered. The product was purified by HPLC on a Waters C-18 bondapak cartridge (Buffer: A=50 mM TEM pH 7.0; B=acetonitrile) using a gradient of 0-25% B in 30 minutes (retention time=22 min.). The product was desalted on a Sep-Pak cartridge and freeze-dried to give 151 mg of 26. Phosphorylation of 2 using the POCl₃ method gave 27. The removal of the trifluoroacetyl group with conc. NH4OH at 50° C. for 30 min to provide the free amine, 28. Conjugation of 28 to 5-carboxyfluoroscein-aminocaproic acid N-hydroxysuccinimide (Fl-X-NHS) under standard conditions provided amide 29. The mass spectral and NMR data for compounds 2.5-29 were consistent with the proposed structures.

Example 4

The compounds of the invention having general formulas I, IA IB, II, III, IIIA. IIIB, and IV as disclosed herein can be prepared using available reagents and procedures that are standard in the art. In addition, examples of these procedures are illustrated in FIGS. 2-10.

Example 5 Procedure for HPLC Analysis of Enzymatic Incorporation of Modified Nucleotides

Reaction Conditions

TdT

3 uM dT₁₆ template

15(30) uM NTP

40 U TdT (Promega)

1× buffer, pH 7.5 (Promega)

Procedure: incubate 1 hr. at 37° C. then for 10 min. at 70° C., followed by the addition of EDTA (2 mM final concentration) in a volume of 50 uL

HPLC Analysis

Materials and Reagents

4.6 mm×250 mm Nucleopac PA-100 ion-exchange column (Dionex) buffer A: 20 mM NaOH (or 20 mM Tris pH 8, in the case of TdT incorporation of nucleotide triphosphates that are not dye-labeled) buffer B: 20 mM NaOH, 1 M NaCl (or 20 mM Tris pH 8, 1 M NaCl, in the case of TdT incorporation of nucleotide triphosphates that are not dye-labeled)

General Procedure

Dilute the reaction with 50 uL of buffer A. Inject 50 uL of this sample onto the HPLC column and fractionate using a gradient of 5 to 100% buffer B over 30 minutes at a flow rate of 1 mL/min. Detect the peaks simultaneously at 260 nm absorbance and the absorbance maximum of the dye (or the fluorescence emmission maximum of the dye).

The incorporation efficiency is expressed as the fraction of oligonucleotide that is labeled. This number is determined by dividing the peak area measured at 260 nm absorbance of the labeled oligonucleotide by the sum of the peak areas of the unlabeled and labeled oligonucleotide. (The retention time of fluorescein-labeled dT₁₆ is on the order of 2 to 3 min. longer than the unlabeled dT₁₆.) The error in this type of assay is about 10%. The percentage labeling efficiency for 4 types of nucleic acid labeling compounds is shown below in Table 1.

Example 6 Labeled N-(2-hydroxyethoxy)ethyl 2-O-triphosphates (Scheme 3)

Compounds having general formula can be prepared using available reagents and procedures that are standard in the art. In addition, examples of these procedures are illustrated in Schemes 3 and FIG. 10.

Example 6A Labeled 2-(2-hydroxyethyl)acetamide 2-O-triphosphates (FIG. 10)

[1,4]Dioxan-2-one, (2-Hydroxy-ethoxy)-acetic acid methyl ester, or a polymer thereof, 33, is reacted with a diamine having a linker moiety, e.g., a polyethylene oxide, alkylene, a combination there of. The labeled compound is prepared by reacting the ether-amine with a suitable labeling compound using standard conditions. The product is converted into a 5′-triphosphate using standard phosphorylation conditions to afford, respectively, nucleic acid labeling compound 36.

Example 7 Synthesis of N-alkyl 2′-amino-2′-deoxyuridine triphosphate (Scheme 4)

4,4-Diethoxy-butylamine is reacted with an activated N-labeled caproyl amine, 37 to provide the N-labeled diethoxy butyl caproyl amide, 38. The amide, 38, is reacted with aqueous hydrochloric acid (0.04 N) to produce the N-labeled aldehyde. the aldehyde is reacted with phosphorylated 1-(3-Amino-4-hydroxy-5-hydroxymethyl-tetrahydro-furan-2-yl)-1H-pyrimidine-2,4-dione, 39, to furnish labeled N-alkyl 2′-amino-2′-deoxyuridine triphosphate, 40. The reaction is illustrated in Scheme 4.

Example 8 Synthesis of 2′-O-(6-(Fluorescein-5-carboxamido)hexyl)uridine 5′-O-triphosphate (Scheme 5)

The protected phthalimide, 41, (available from RI Chemicals, 500 mg), is reacted successively with a) hydrazine/ethanol, b) Trifluoroacetic acid-imidazole at 0° C. and c) Acetic acid/methanol to provide compound, 42. The alcohol-amine is converted into a 5′-triphosphate using standard phosphorylation conditions followed by conjugation to a label to afford, respectively, nucleic acid labeling compounds, 43.

Example 9 Synthesis of 2′-S(N-(6-(Fluorescein-5-carboxamido)hexyl)aminoethyldithiouridine 5′-O-triphosphate (Scheme 6)

3-Hydroxy-2-hydroxymethyl-2,3,3a,9a-tetrahydro-furo[2′,3′:4,5]oxazolo[3,2-a]pyrimidin-6-one, 44, is treated with acetic anhydride in pyridine to protect the hydroxy groups. The protected compound, 45, is reacted with thioacetic acid/dioxane at 100° C., according to the procedure in J. Chem. Soc. Perkin Trans 1, 1997, 2587. the product is treated with ammonia provide thiol, 46. The thiol is reacted with disulfide, 99, to provide disulfide, 47. the disulvide is converted into a 5′-triphosphate using standard phosphorylation conditions followed by reaction with a labeled reagent to afford, respectively, nucleic acid labeling compounds, 43.

All patents, patent applications, and literature cited in the specification are hereby incorporated by reference in their entirety. In the case of any inconsistencies, the present disclosure, including any definitions therein will prevail.

The invention has been described with reference to various specific and preferred embodiments and techniques. However, it should be understood that many variations and modifications may be made while remaining within the spirit and scope of the invention. 

1. A nucleic acid labeling compound having the formula:

wherein A is hydrogen, monophosphate, diphosphate, triphosphate, α-thiotriphosphate, phosphoramidite, or H-phosphonate; wherein X₁ is O, S, NR₁ or CHR₂, wherein R₁ and R₂ are, independently, hydrogen, alkyl or aryl; wherein X₂ is a bond or alkylene; wherein Q is selected from the group consisting of a radiolabel, a magnetic particle, colloidal gold, fluorescein, texas red, rhodamine, green fluorescent protein, luminal lophine, acridine salts, luciferin, vanadium spin labels, copper spin labels, iron spin labels, manganese spine labels, nitroxide free radicals, quinoline dyes, triarlmethane dyes, acridine dyes, colored glass beads, polystyrene beads, polypropylene beads, latex beads, biotin, horseradish peroxidase, alkaline phosphatase, 1-aminonapthalene, 2-aminonapthalene, p,p′-diaminostilbenes, pyrenes, quaternary phenanthridine salts, 9-aminoacridines, p,p′-diaminobenzophenone imines, anthracenes, oxacarbocyanines, marocyanine, 3-amino aminoequilenin, perylene, bisbenzoxazole, bis-p-oxazolyl benzene, 1,2-benzophenazin, retinol, bis-3-aminopridinium salts, hellebrigenin, tetracyline, sterophenol, benzimidazolyl phenylamine, 2-oxo-3-chromen, indole, xanthen, 7-hydroxycoumarin, phenoxazine, salycilate, strophanthidin, porphyrins, triarylmethanes, flavin, xanthene dyes, rhodamine dyes, cyanine dyes, 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene dyes, phycobiliprotein, dansyl chloride, 3,6-dihydroxy-9-phenylxanthhydrol; rhodamineisothiocyanate; N-phenyl-1-amino-8-sulfonatonaphthalene; N-phenyl-2-amino-6-sulfonatonaphthalene; 4-acetamido-4-isothiocyanatostilbene-2,2′-disulfonic acid; pyrene-3-sulfonic acid; 2-toluidinonapththalene-6-sulfonate; N-phenyl, N-methyl 2-aminonaphthalene-6-sulfonate; ethidium bromide; stebrine; auromine-0,2-(9′-anthroyl)palmitate; dansyl phosphatidylethanolamin; N,N′-dioctadecyl oxacarbocycanine; N,N′-dihexyl oxacarbocyanine; merocyanine, 4-(3′-pyrenyl)butryate; d-3-aminodesoxy-equilenin; 12-(9′-anthroyl)stearate; 2-methylanthracene; 9-vinylanthracene; 2,2′-(vinylene-p-phenylene)bisbenzoxazole; p-bis[2-(4-methyl-5-phenyl oxazolyl)]benzene; 6-dimethylamino-1,2-benzophenzin; retinol; bis(3′-aminopyridinium)-1,10-decandiyl diiodide; sulfonaphthylhydrazone of hellibrienin; chlorotetracycline; N-(7-dimethylamino-4-methyl-2-oxo-3-chromenyl)maleimide; N-[p-(2-benzimidazolyl)phenyl]maleimide; N-(4-fluoranthyl)maleimide; bis(homovanillic acid); resazarin; 4-chloro-7-nitro-2,1,3-benzooxadizole; merocyanine 540; resorufin; rose_bengal and 2,4-diphenyl-3(2H)-furanone; and wherein G is -L-(M)_(m), wherein L is a linker moiety selected from the group consisting of amido alkyl groups, functionalized alkyl groups, alkenyl alkyl groups, alkanoyl groups, and N-alkyl amido groups, wherein m is an integer from 0 to 20 and each M is a connecting group selected from the group consisting of amino alkyl, —O(CH₂)₅NH—, —CO—, —NH—, —CO(O)—, —CO(NH)—, —(CH₂)_(i)O—, —(CH₂)_(j)NH—, —C(O)(CH₂)_(h)O—, —CO(CH₂)₅NHCO(CH₂)₅NH—, —NH(CH₂CH₂O)_(k)NH—, —NH(CH₂CH₂O)_(k)CH₂CH₂NH— and —CO(CH₂)₅—, wherein k is an integer from 1 to 5, and wherein h, i, and j are independently integers from 1 to
 5. 2. The nucleic acid labeling compound of claim 1, wherein A is H or H₄O₉P₃—; wherein X₁ is O; wherein X₂ is a bond; and wherein G is —C(O)NR₃—(CH₂)_(m)—(CH₂CH₂O)_(n)—CH₂CH₂—C(O)NR₃—, wherein R₃ is hydrogen or alkyl, and wherein m and n are independently an integer from 1 to
 15. 3. The nucleic acid labeling compound of claim 2, wherein G is —C(O)NH—(CH₂)_(m)—(CH₂CH₂O)_(n)—CH₂CH₂—C(O)NH—; wherein m is from 1 to 6; and wherein n is from 1 to
 4. 4. The nucleic acid labeling compound of claim 1, wherein A is H or H₄O₉P₃—; wherein X₁ is O; wherein X₂ is CH₂; and wherein G is —C(O)NR₃—(CH₂)_(m)—(CH₂CH₂O)_(n)—CH₂CH₂—C(O)NR₃—, wherein R₃ is hydrogen or alkyl, and wherein m and n are independently an integer from 1 to
 15. 5. The nucleic acid labeling compound of claim 4, wherein G is —C(O)NH—(CH₂)_(m)—(CH₂CH₂O)_(n)—CH₂CH₂—C(O)NH—, wherein m is from 1 to 6, and wherein n is from 1 to
 4. 